Define a series of AMPLITUDEs that describe the load variation with time at each x nodal position along the beam
Then apply loads as follows on each respective node along the beam:
*CLOAD, AMPLITUDE=AMP1
NODE1, 2, 1.0
*CLOAD, AMPLITUDE=AMP2
NODE2, 2, 1.0
*CLOAD, AMPLITUDE=AMP3
NODE3, 2, 1.0
etc
where 'NODE1'.... are the node sets or node numbers.
The AMPLITUDEs will progressively increase and then decrease the load on each node.